1. Field of the Invention
The present invention relates to the manufacture of pile fabric, and in particular to the formation of textured pile fabric on a warp knitting machine wherein a pattern is formed thereon by pile threads of different length.
2. Description of the Relevant Art
A process used in the manufacture of woven materials utilizes partial weft threads, which at the turning position, are bound off with the stitches of the base fabric. The portions between the turning positions lie freely on the base fabric to form hollow ribs. The ribs are then individually cut open to provide pile ribs.
Utilizing this procedure only straight warp ribs may be provided as the pile pattern. Also, it is not possible to provide pile threads of the same length to each adjacent stitch in the warp direction so that either a pile of lesser density or a pile without a distinct high profile characteristic is provided. Moreover, it is not possible to provide a pile rib which has a lower height or thickness at the edge than in the center of the rib or a rib which has different pile thread lengths in each stitch row. Since the segments to be cut apart must correspond to a separation of several needle widths, the height of the pile cannot be freely chosen. Moreover, the width of the ribs are limited since the length of the pile threads becomes too long when greater rib widths are chosen. The cutting open of the hollow ribs is tedious, time consuming, expensive and subject to substantial errors which reduce the yield of the ware. It is necessary to utilize a thread cutting needle which utilizes two separate shafts that is inserted into each rib opening space by manual means. These needles often stray into the material and either cut the material or break the needle. A manually introduced circular knife cuts the partial weft threads forming the hollow ribs by inserting between the two shafts of the thread cutting needle. Since the pile threads cut open in this manner lie flat on the base fabric, they must be subjected to an additional brushing operation in order to have them stand upright.